EPA has proposed a number of modifications in existing assessment approaches and new policies regarding assumptions or methods. Some policy actions have occurred in response to new scientific information whereas in other cases EPA has acted to better protect itself from legal actions or threats from pesticide opponents or to cater to the changing political climate. In some cases, policies and procedures required for components of registration review have yet to be developed or finalized. Since chlorpyrifos will be one of the first major products moving through registration review, there are some key issues and areas to watch as EPA works towards completing chlorpyrifos human health and environmental assessments.

Consumer Exposure Assessment

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Go to the regulatory review schedule for chlorpyrifos to see dates for open comment periods.

For a number of years EPA has relied upon both field residue studies generated by registrants and residue monitoring data collected by USDA to prepare highly refined assessments of human dietary exposure to residues that may occur in food or water. EPA is in the process of revising its approach to estimating drinking water exposures. Rather than utilize real-world monitoring data, which shows no detections of chlorpyrifos residues in finished water delivered to customers, the Agency is considering using worst-case computer modeling estimates as a more conservative estimate of potential drinking water exposures. Dow AgroSciences and other stakeholders believe it is important to use realistic estimates based on real-world information with respect to drinking water exposures.

Read more about protecting consumers.

Bystander Exposures to Airborne Pesticide Residues

In the past, EPA assessments included consideration of inhalation exposures to farmworkers and professional applicators during handling and application of pesticides. EPA is now moving to also consider bystander exposures due to inhalation of airborne residues resulting from spray drift or evaporation from treated crops. The Agency’s proposed methodology for estimating bystander exposure to airborne residues is highly conservative and was reviewed by the EPA Scientific Advisory Panel during December of 2009. A first assessment of potential chlorpyrifos spray drift exposures to bystanders was prepared by EPA during 2012, and an assessment of potential vapor exposures is expected in the future.

Read more about protecting bystanders from chlorpyrifos exposure.

Farmworker Exposure Assessment

In association with a new “Environmental Justice” policy initiative, EPA during December of 2009 announced several proposed changes in how farmworker exposure assessments would be conducted. These changes included aggregating workplace and consumer exposures and adopting more conservative assumptions to account for teen workers and children of farmworkers who may be present in and around agricultural fields. Announcement of these proposed changes prompted a significant amount of public feedback, including concerns with implications of labor codes, and EPA has yet to announce the final approaches it will employ.

Read more about exposure assessment, protection, and monitoring for farm workers.

Assessment of Epidemiology Research Studies

Epidemiology studies are surveys of human population and health records which attempt to correlate observed health outcomes with potential causative factors. Through a series of statistical analyses these studies attempt to determine any differences in health effects that may be correlated to pesticide exposures. There are many confounding factors involved in interpreting such studies including simultaneous exposure to multiple chemicals and difficulties with documenting exposures, and EPA’s proposed approach was reviewed by the Scientific Advisory Panel during February of 2010. The Panel advised EPA to develop significant revisions in its approach, and the crop protection industry has recently petitioned EPA to take action regarding recommended improvements. Many experts believe that a weight-of-the-evidence approach that considers data from both laboratory guideline studies and epidemiology studies in an integrated fashion is most appropriate, and Dow AgroSciences supports this view.

Endocrine Disruption Potential

Exposure to some chemicals has been shown to interfere with proper function of endocrine-related hormone systems of humans or wildlife. The Food Quality Protection Act of 1996 mandated that EPA develop a new testing program to determine which chemicals, including pesticides, may cause such effects and whether existing exposure standards are protective enough for such effects. After a number of years of scientific and policy debate, EPA launched an Endocrine Disruptor Screening Program in 2009 which introduced a new battery of Tier I screening level laboratory tests for which 70 chemicals and pesticides were initially selected for testing based on volume of use. Chlorpyrifos was one of these initial products, and Dow AgroSciences has completed the assays, which along with other products are now under review by EPA. A weight-of-evidence evaluation of the assays by Dow scientists concluded that chlorpyrifos is not active as an endocrine disruptor and no further testing appears warranted, but EPA’s assessment is awaited.

Endangered Species Assessment

Under terms of the Endangered Species Act (ESA), EPA is required to consider potential impacts on survival of threatened or endangered plants and animals in making its registration and registration review decisions. Where concerns may exist, EPA is required to seek advice from either the U.S. Fish and Wildlife Service (USFWS) or National Marine Fisheries Services (NMFS) depending on where the species lives. Although EPA has developed several initiatives related to methods for assessment of endangered species impacts and has announced intentions of implementing them as part of registration review, serious process and science disagreements between EPA and USFWS and NMFS have so far thwarted progress. EPA and many experts believe that the Agency’s conservative assessments for fish, birds and other wildlife are already protective of endangered species, but pesticide opponents have seized on the federal agency disagreements and brought lawsuits that have pretty much brought cooperative assessment efforts to a halt. As Congressional hearings have considered potential areas of process improvements, so also EPA, USFWS, and NMFS have sought the advice of a panel of experts formed by the National Academy of Sciences to untangle the scientific issues. Dow AgroSciences and other registrants are monitoring developments closely and, along with grower organizations, counseling adoption of realistic, down-to-earth approaches to endangered species assessment for use during registration review.